Numbers 32
29 And Moses said to them, If the children of Gad and the children of Reuben go with you over Jordan, every man armed for the fight before the Lord, and all the land is given into your hands, then let them have the land of Gilead for a heritage:
30 Ref But if they do not go over with you armed, they will have to take their heritage with you in the land of Canaan.
31 Then the children of Gad and the children of Reuben said, As the Lord has said to your servants, so will we do.
32 We will go over armed before the Lord into the land of Canaan, and you will give us our heritage on this side of Jordan.